Merge pull request #20922 from alexrp/vdso

`std.os.linux`: Fix VDSO for mips, add VDSO for riscv

Author: andrewrk

lib/std/os/linux.zig

@@ -1397,7 +1397,7 @@ const VdsoClockGettime = *align(1) const fn (clockid_t, *timespec) callconv(.C)
 var vdso_clock_gettime: ?VdsoClockGettime = &init_vdso_clock_gettime;
 
 pub fn clock_gettime(clk_id: clockid_t, tp: *timespec) usize {
-    if (@hasDecl(VDSO, "CGT_SYM")) {
+    if (VDSO != void) {
         const ptr = @atomicLoad(?VdsoClockGettime, &vdso_clock_gettime, .unordered);
         if (ptr) |f| {
             const rc = f(clk_id, tp);

lib/std/os/linux/mips.zig

@@ -242,8 +242,8 @@ pub const F = struct {
 pub const MMAP2_UNIT = 4096;
 
 pub const VDSO = struct {
-    pub const CGT_SYM = "__kernel_clock_gettime";
-    pub const CGT_VER = "LINUX_2.6.39";
+    pub const CGT_SYM = "__vdso_clock_gettime";
+    pub const CGT_VER = "LINUX_2.6";
 };
 
 pub const Flock = extern struct {

lib/std/os/linux/mips64.zig

@@ -227,8 +227,8 @@ pub const F = struct {
 pub const MMAP2_UNIT = 4096;
 
 pub const VDSO = struct {
-    pub const CGT_SYM = "__kernel_clock_gettime";
-    pub const CGT_VER = "LINUX_2.6.39";
+    pub const CGT_SYM = "__vdso_clock_gettime";
+    pub const CGT_VER = "LINUX_2.6";
 };
 
 pub const Flock = extern struct {

lib/std/os/linux/riscv32.zig

@@ -188,7 +188,10 @@ pub const Elf_Symndx = u32;
 
 pub const MMAP2_UNIT = 4096;
 
-pub const VDSO = struct {};
+pub const VDSO = struct {
+    pub const CGT_SYM = "__vdso_clock_gettime";
+    pub const CGT_VER = "LINUX_4.15";
+};
 
 /// TODO
 pub const ucontext_t = void;

lib/std/os/linux/riscv64.zig

@@ -215,7 +215,10 @@ pub const Stat = extern struct {
 
 pub const Elf_Symndx = u32;
 
-pub const VDSO = struct {};
+pub const VDSO = struct {
+    pub const CGT_SYM = "__vdso_clock_gettime";
+    pub const CGT_VER = "LINUX_4.15";
+};
 
 /// TODO
 pub const ucontext_t = void;